Horsefeathers! Inline sixes are made to lug. The only time it does any damage is if there is an excessive carbon buildup or incorrect ignition timing that would cause preignition, which leads to detonation. As long as the bearings don't have excessive clearance and tie oil pressure is good, go ahead and lug it down if necessary.
Jerry
In 1970 my dad had a 194 ci cyl in Chevy that tow bared my 1935 Buick home from near Watertown, NY to Long Island. About 400 miles.
About a week after we were home that 6 cyl had a connecting rod blow a hole in the side of the block.
